1. Field of the Invention
The present invention relates to a method and a device for winding a magnetic tape, such as winding a magnetic tape of prescribed length from a source roll of a magnetic tape to a small reel, rewinding a magnetic tape from one reel to another, winding a magnetic tape of large width for a source roll, and winding a magnetic tape of large width to a plurality of reels while slitting the tape.
2. Background of the Invention
A process of manufacturing a magnetic tape such as an audio cassette tape, a video cassette tape, a memory tape and a broadcasting video tape includes a step of winding a magnetic tape of prescribed length from a source roll of a large-length tape to a small tape winding body such as a reel and a hub, a step of rewinding a magnetic tape from a tape winding body to another tape winding body, a step of winding a magnetic tape of large width as source tape, a step of winding a magnetic tape slit from another magnetic tape, and so forth. When the magnetic tape is wound on the tape winding body in the process of the winding or the rewinding, such behavior of the tape as its vibration in the direction of the thickness of the tape and its vibration in the direction of the width of the tape can fluctuate due to the physical properties of the magnetic tape and those of the tape winding body so that each side edge of the tape wound on the winding body is unneatly overlaid on itself. The higher the speed of the winding is, the more unneatly the side edge is overlaid on itself.
A magnetic tape whose side edge is unneatly overlaid on itself as described above has problems of poor external appearance of the wound tape housed as a commercial product in a magnetic tape cassette and the side edge is likely to be damaged resulting in various troubles such as the deterioration of the electromagnetic conversion properties of the tap. The unneat overlaying is a serious drawback, particularly for a magnetic video tape for high-density recording because an audio signal or a tuning signal is recorded near the side edge of the tape. For these reasons, in a conventional process of manufacturing a magnetic tape, the wound reels of all magnetic tape are visually inspected after a winding process or a rewinding process. Since the inspection takes much time and money, the inspection is a major disadvantage of the magnetic tape manufacturing process.
Conventional system, which are shown in FIGS. 1 and 2 and are what is called neat winding, have been adopted to wind a magnetic tape of otherwise low neatwinding yield in order to improve the wound state of the tape to reduce the necessity of inspection thereof. FIGS. 1 and 2 show perspective schematic views of tape winding bodies 2 and the vicinity thereof.
In the conventional system shown in FIG. 1, an endless flexible belt 11 made of rubber, polyimide or the like and rotatably supported by rollers 12, 13 and 14 is revolved together with the magnetic tape T and elastically pushes the magnetic side of the tape in the radial direction of the tape winding body 2 to neatly wind the tape.
In the other conventional system shown in FIG. 2, a belt 15 made of a relatively soft nonwoven fabric or the like is provided between one flange of the tape winding body 2 and one side edge of the magnetic tape T to push the side edge of the tape. Meanwhile, the belt 15 is supported by a roller 17 or the like and wound at a low constant speed from a belt supply spool 16 to a belt winding spool 18, so as to neatly wind the tape.
However, since the belts 11 and 15 are placed in direct contact with the magnetic tape T in the above-mentioned systems, there are various problems that the magnetic layer of the tape is worn or the fibers of the nonwoven fabric come off to locally hinder recording on the tape, inappropriate pressure acts to deform the tape or damage its side edge, and so forth. For that reason, the systems do not function properly. In addition, since the wear and tear of the neat winding systems are large, they have disadvantages with regard to their cost and maintenance as well. The construction of each of the systems needs to be such that the tape winding body 2 is moved between at least a working position and a non-working position when it is replaced. This construction makes the magnetic tape winding device complicated and renders it relatively time-consuming to replace the tape winding body. The period of time of the movement of the tape winding body hinders the improvement of productivity.
Two systems for winding a magnetic tape for a cassette are used today. One of them is an open winding system in which the tape is neatly wound and then inserted into the cassette so as to be a finished product. The other is an in-cassette winding system which is also called C-O winding system or V-O winding system and in which the tape is wound at the final stage of assembly of the cassette.
As for the in-cassette winding system, as illustrated in FIG. 3, the cassette 23 without the magnetic tape is first assembled, an outgoing tape winding body 2 and an incoming tape winding body 3 which are coupled to each other by a leading tape 10 are inserted into the cassette 23 and screws are tightened so as to provide an unfinished product generally called V-O, C-O or the like. In the unfinished product, the leading tape 10 is partly pulled out by an in-cassette winder and cut off in the middle. The front end of a magnetic tape T is joined to one cut-off end of the leading tape 10 whose other cut-off end is held by a suction member 22. The tape winding body 2 having the leading tape joined to the magnetic tape T is rotated to wind a prescribed length of the magnetic tape T on the body 2. The magnetic tape T is then cut off. The rear end of the magnetic tape T wound on the winding body 2 is then joined to the other cut-off end of the leading tape 10, thus finishing the product. Since the wound state of the magnetic tape T entirely depends on the physical properties of the tape and the accuracy of the assembly of the cassette, the wound state cannot be controlled to be good. For that reason, the yield of well-wound magnetic tapes is low.
In order to increase the yield, a roller 24, shown in FIG. 4, having an upper and a lower flanges 25 has been provided on a trial basis to apply a force to the magnetic tape in the direction of the width thereof to push the tape sideward. However, after all, there is no good means available to improve the wound state of the magnetic tape.
Although the conventional winding systems shown in FIGS. 1, 2, 3 and 4 are used for neatly winding a magnetic tape after the tape is made as source tape or as a tape of smaller width, yet another magnetic tape of a large width and not yet made into a source tape has also been desired to be neatly wound without using a member such as a flange which restricts the motion of the side edge of the tape.
The use of magnets to align a magnetic tape is disclosed in Japanese Patent Application No. 51642/86, Japanese Patent Applications Nos. 16886/86, 48899/86 and 48900/86 (combined into a corresponding U.S. patent application Ser. No. 008040, filed Jan. 20, 1987) and 16887/86 and 57581/86 (combined into a corresponding U.S. patent application Ser. No. 008494, filed Jan. 22, 1987).